Electricity is measured in amperes or amps, with an ampere being the amount of electric charge that flows through a conductor in a given time. Electrical devices are classified according to their amperage, and amperage must be controlled to protect wiring and electrical circuits from overheating or shorting. In the event of an electric shock, it is the amount of current flowing through the body, not the voltage, that determines the severity of injuries. The higher the current rating, the higher the cost of running an appliance, and there is a trade-off between power and economy when it comes to electrical devices.
Amperage is a term often used by electricians and means electric current, measured in amperes or amps. The ampere is the SI unit for electric current, or the amount of electric charge that flows through a conductor in a given time. An ampere is a charge of one coulomb – approximately 6,241 X 1018 electrons – per second flowing past a given point. Electrical devices are classified according to their amperage, or the amount of current they typically draw from a mains supply when operating normally. When electricians talk about the electricity flowing in and out of a home, they may be referring to voltage, amperage, or wattage depending on the circumstances, but when considering the effects of an electric shock, it is the amperage, rather than the voltage, that it’s important.
Ampere and Volt
Electricity is to domestic electrical circuits what water is to domestic plumbing systems. Voltage is roughly equivalent to water pressure and amperage, or current, to the amount of water flowing past a given point per second. At a given pressure, less water can pass through a small pipe than a large one in a given time, so the size of the pipe can be considered equivalent to a measure of electrical resistance: a smaller pipe has a higher resistance. The higher the electrical resistance of an appliance, the lower its current will be, and the resistance often depends on the diameter of the wires.
Electricity is brought into the house through power lines ultimately connected to a generator. To minimize energy loss through the resistance of power lines, transformers are used to transmit power at very high voltages. Before it reaches homes, however, additional transformers are used to step the voltage down to a value suitable for home use, which is 110 volts in the US, but 230 volts in Europe, for example. Voltage is a measure of the “potential” energy available, not necessarily how much is actually being used.
This is where amperage comes in: An electrical appliance needs a certain amount of electricity to do its job, and it draws that amount of electricity from the “river” of volts in the line. A small appliance, like a toaster oven, usually requires less energy than a larger appliance like a refrigerator or electric saw. In electrical terms, these appliances operate at different current ratings. A large electric motor can draw 100 amps of current, while a small heating element can only draw ten amps. Both draw on the same 110-volt line, but their current needs are vastly different.
Energy consumption
Watts are the units used to measure energy consumption. A one volt amplifier current uses one watt of power. The power used by a device is simply amps multiplied by volts, so an appliance rated at ten amps plugged into a 110-volt power supply will use 1.110 watts. Because watts are used by power companies to measure the electricity they consume and to charge customers, amperage is important in calculating the cost of running an electrical device. Typically, consumers will be charged based on the kilowatt-hours of energy consumption: running a ten-amp device on a 110-volt supply for one hour will draw 1.110 watt-hours, or 1.11 kilowatt-hours.
The rule of thumb for homeowners is that the higher the current rating, the higher the cost of running an appliance. There is always a trade-off between power and economy when it comes to electrical devices. If saving on your monthly bills is a priority, you should select products with lower amperage. If power and speed are more important, products with higher current are generally better.
Protection of household appliances
Amperage must be controlled to protect wiring and electrical circuits from overheating or shorting. This is why electricians use fuses and circuit breakers. A 30-amp fuse, for example, will allow smaller appliances to run on the line it protects, but if an electric clothes dryer draws 60 amps, a metal filament in the fuse will melt and immediately break the circuit. Circuit breaker switches also control the current through the circuit break. Larger electrical devices often have their own circuits with larger capacity fuses or circuit breakers to prevent such overloads.
Electro-shock
In the event that a person receives an electric shock through negligence or an electrical fault, it is the amount of current flowing through the body, and not the voltage, that determines the severity of the injuries caused and the likelihood of death. Many high school students will have experienced a shock of perhaps 50,000 volts from a Van de Graaf generator in the physics lab, but this produces an extremely small current and is harmless. On the other hand, a 110 volt shock, with a current of just a small fraction of an amp, could be fatal. A current of 0.1-0.2 amperes flowing through a human body is usually lethal, due to its effects on the heart. Surprisingly, with prompt treatment, victims exposed to more than 0.2 amps can survive, as the severe induced muscle contractions can protect the heart from electrical interference.
Protect your devices with Threat Protection by NordVPN
